Air supply system for a motor vehicle

CROSS REFERENCE TO RELATED APPLICATION

0001This application claims priority of German patent application no. 103 22 578.1, filed May 20, 2003, the entire content of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

0002Air supply systems are utilized especially for supplying air spring damper units for the leveling control of a motor vehicle within a closed loop but also to supply external consumers.

0003U.S. Pat. No. 6,726,189 discloses one such air supply system in various embodiments.

0004In the first embodiment of <figref idref="DRAWINGS">FIG. 1</figref> of this patent, the air supply system comprises: several air spring damper units arranged in parallel to each other, a compressor and a pressurized air store. A 2/2-directional valve is assigned to each air spring damper unit and the air spring damper units are connected via a common ring line to the intake end as well as to the pressure end of the compressor. In this ring line, a switchable intake valve is also provided. A second ring line connects the pressurized air store to the intake end and to the pressure end of the compressor. In this ring line, an air dryer is arranged on the pressure end which has a free flow via a throttle check valve in the through-flow direction to fill the pressurized air store and this through-flow is throttled in the opposite through-flow direction for flushing the air dryer.

0005In this air supply system, the compressor can transfer pressurized air from the air spring damper units into the pressurized air store and, in the opposite direction, fill the air spring damper units with air from the pressurized air store. Furthermore, the compressor can supply the air spring damper units or the pressurized air store with fresh air from the atmosphere. A further function comprises venting pressurized air into the atmosphere from the pressurized air store in the opposite direction via the air dryer in order to regenerate the latter. Several directional valve units are provided in both ring lines to realize these various functions. Accordingly, and in accordance with <figref idref="DRAWINGS">FIG. 1</figref>, two parallelly-connected 2/2-directional valves are used for the first ring line and two likewise parallelly-connected 2/2-directional valves are used for the second ring line.

0006This embodiment of the air supply system has the disadvantage that no consumer, which lies outside of the closed loop, can be supplied with pressurized air. In this way, the power capacity of the compressor is not fully utilized.

0007Accordingly, in FIG. 8 of U.S. Pat. No. 6,726,189, a second embodiment provides for a branching between the compressor and the air dryer for a line connection to supply an external consumer. With this embodiment of the air supply system, for example, a tire-fill apparatus can be operated as shown.

0008This embodiment has the disadvantage that it is very complex and therefore very expensive with respect to its manufacture. This is caused by the additional units for tire filling and has its cause, however, also in the plurality of 2/2-directional valves required for the closed loop.

SUMMARY OF THE INVENTION

0009In view of the above, it is an object of the invention to provide an air supply system for supplying consumers of a closed loop and for additionally supplying at least one external consumer with this air supply system having a reduced number of directional valves.

0010An air supply system of the invention is for a motor vehicle. The air supply system is for supplying consumer means of a closed loop and for supplying an external consumer and includes: a pressurized air store; an intake connection communicating with the atmosphere; a compressor; a first consumer pressure line; a second consumer pressure line connected to the external consumer; a store pressure line connected to the compressor; a first switchable 3/2-directional valve arranged in the first consumer pressure line; a second switchable 3/2-directional valve arranged in the store pressure line; the first and second 3/2-directional valves being configured so that: (a) the compressor conveys fresh air from the atmosphere through the intake connection to the pressurized air store; and/or, (b) the compressor conveys fresh air to the external consumer and transfers already compressed pressurized air between the consumer means and the pressurized air store; a check valve in the store pressure line; a bypass line connected into the store pressure line to bypass the check valve; a throttle connected into the bypass line; and, a switchable blocking valve arranged in the bypass line to disable the functioning of the throttle.

0011The new air supply system eliminates the above-mentioned disadvantages of the state of the art. Accordingly, only two 3/2-directional valves are needed compared to four 2/2-directional valves in accordance with the closest state of the art. This simplifies the configuration of the pneumatic loop and thereby reduces the manufacturing cost of such an air supply system. The special advantage of the new air supply system is that, in the phase for filling the vehicle tires, dry and compressed air from the pressurized air supply cannot escape either via the intake line and the running compressor or via the non-used store pressure line and the dryer and cannot mix with the fresh air flow drawn in by suction for filling the tires. The leakage via the compressor is prevented by the pressure position of the 3/2-directional valve in the store pressure line and the switchable check valve in the bypass line of the store pressure line prevents the escape of the pressurized air via the dryer. The pressure position of the 3/2-directional valve blocks the intake line.

0012It is also advantageous that the additional check valve is a 2/2-directional valve and is mounted in the bypass line because, in this way, the 2/2-directional valve can be configured to be built very small because of the throttled and therefore reduced bypass flow. The additional complexity is, in addition, still reduced in that the additional 2/2-directional valve and the bypass throttle are combined in a valve combination.

0013It is also advantageous if the line, which extends from the switchable outlet valve of the directional valve unit into the atmosphere, is utilized as a second consumer pressure line for the supply of the external consumer. This saves additional complexities for the realization of the second consumer pressure line.

BRIEF DESCRIPTION OF THE DRAWING

0014The invention will now be described with reference to the single figure (<figref idref="DRAWINGS">FIG. 1</figref>) of the drawing which shows the closed loop of an air supply system for the level control of a motor vehicle.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

0015The air supply system of the invention essentially comprises: a drive unit <b>1</b>, a directional valve unit <b>2</b>, four air spring damper units <b>3</b> to <b>6</b> and a pressurized air store <b>7</b>.

0016The primary component of the drive unit <b>1</b> is a compressor <b>8</b> which is driven by an electric motor M and which, on the one hand, is connected via an intake line <b>9</b> to an intake connection <b>10</b> leading into the atmosphere. On the other hand, the compressor <b>8</b> has a store pressure line <b>11</b> which leads via a dryer <b>12</b> and a check valve <b>13</b> to a store connection <b>14</b>. The store connection <b>14</b> of the drive unit <b>1</b> is connected to the pressurized air store <b>7</b> and an intake valve <b>15</b>, which is connected to the atmosphere, is disposed between the store connection <b>14</b> and the pressurized air store <b>7</b>. The check valve <b>13</b> is arranged in the store pressure line <b>11</b> so that it opens in the direction toward the pressurized air store <b>7</b>. In addition, a bypass line <b>16</b> is disposed in the store pressure line <b>11</b>. The bypass line <b>16</b> bypasses the check valve <b>13</b> and the following are arranged in the bypass line <b>16</b>: a bypass throttle <b>17</b> and an electromagnetically-controlled 2/2-directional valve <b>18</b> which disables the bypass throttle <b>17</b>.

0017A first consumer pressure line <b>19</b> branches away from the store pressure line <b>11</b> between the compressor <b>8</b> and the dryer <b>12</b>. The first consumer pressure line <b>19</b> leads to a first consumer connection <b>20</b>. This first consumer connection <b>20</b> of the drive unit <b>1</b> is connected to the directional valve unit <b>2</b>.

0018The directional valve unit <b>2</b> includes four 2/2-directional valves <b>21</b> to <b>24</b> which are controlled electromagnetically and which are arranged in parallel to each other. The four 2/2-directional valves <b>21</b> to <b>24</b> each connect the first consumer connection <b>20</b> of the drive unit <b>1</b> to respective ones of the four air spring damper units <b>3</b> to <b>6</b>. A switchable venting valve and a pressure sensor <b>26</b> are disposed in the directional valve unit <b>2</b>. The venting valve <b>25</b> connects or interrupts the first consumer connection <b>20</b> of the drive unit <b>1</b> and the atmosphere and the pressure sensor <b>26</b> checks the pressure in the first consumer pressure line <b>19</b>.

0019The drive unit <b>1</b> also includes a second consumer connection <b>27</b> which connects the compressor <b>8</b> to a filling apparatus <b>29</b> for a vehicle tire <b>30</b> via a second consumer pressure line <b>28</b>.

0020A first electromagnetically-controlled 3/2-directional valve <b>31</b> is arranged within the drive unit <b>1</b> and in the first consumer pressure line <b>19</b>. The 3/2-directional valve <b>31</b> is, on the one hand, connected to the pressure end of the compressor <b>8</b> and to the intake end of the compressor <b>8</b> and, on the other hand, to the directional valve unit <b>2</b>. A second 3/2-directional valve <b>32</b> is disposed in the store pressure line <b>11</b> of the drive unit <b>1</b> between the 2/2-directional valve <b>18</b> of the bypass line <b>16</b> and the store connection <b>14</b>. The 3/2-directional valve <b>32</b> is likewise connected, on the one hand, to the pressure end of the compressor <b>8</b> and to the intake end of the compressor <b>8</b> and, on the other hand, to the pressurized air store <b>7</b>.

0021To fill the pressurized air store <b>7</b> with fresh air from the atmosphere, the compressor <b>8</b> draws the fresh air via the intake connection <b>10</b> and pumps the air via the dryer <b>12</b>, the opening check valve <b>13</b> and the 3/2-directional valve <b>32</b> (in the shown pressure position) into the pressurized air store <b>7</b>. A part of the pumped flow flows also via the bypass throttle <b>17</b> and the open 2/2-directional valve <b>18</b> in the bypass line <b>16</b>. The 3/2-directional valve <b>31</b> in the consumer pressure line <b>19</b> is blocked in the pressure position shown so that no pressurized air reaches the directional valve unit <b>2</b>.

0022To fill one or several air spring damper units <b>3</b> to <b>6</b> with compressed pressurized air from the pressurized air store <b>7</b>, the 3/2-directional valve <b>32</b> in the storage pressure line <b>11</b> is switched into the intake position and the 3/2-directional valve <b>31</b> in the first consumer pressure line <b>19</b> is switched into the pressure position shown. The compressor <b>8</b> draws the pressurized air via the 3/2-directional valve <b>32</b> and moves the pressurized air into the first consumer pressure line <b>19</b> and there, to the selected air spring damper units <b>3</b> to <b>6</b> via the 3/2-directional valve <b>31</b> and the corresponding 2/2-directional valve <b>21</b> to <b>24</b> of the directional valve unit <b>2</b>.

0023To transfer excessive and dry pressurized air from one or several air spring damper units <b>3</b> to <b>6</b> back into the pressurized air store <b>7</b>, the 3/2-directional valve <b>31</b> in the first consumer pressure line <b>19</b> is in the intake position and the 3/2-directional valve <b>32</b> of the store pressure line <b>11</b> is in the pressure position. The compressor <b>8</b> then draws via the consumer pressure line <b>19</b> from the directional valve unit <b>2</b> and conveys into the store pressure line <b>11</b> to the pressurized air store <b>7</b>.

0024To regenerate the dryer <b>12</b>, excessive and dry pressurized air is released from the pressurized air store <b>7</b> and is conducted opposite to the fill direction via the dryer <b>12</b> and discharged into the atmosphere. For this purpose, the 3/2-directional valve <b>31</b> in the first consumer line <b>19</b> is in the shown pressure position and the switchable venting valve <b>25</b> is in the open position.

0025To fill an external vehicle tire <b>30</b> with fresh air from the atmosphere, the 3/2-directional valve <b>32</b> of the store pressure line <b>11</b> and the 3/2-directional valve <b>31</b> of the first consumer pressure line <b>19</b> are switched into the respective pressure positions. Here, all 2/2-directional valves <b>21</b> to <b>24</b> and the switchable venting valve <b>25</b> of the directional valve unit <b>2</b> are in the blocked position in order to prevent fresh and therefore moist pressurized air from reaching the air spring damping units <b>3</b> to <b>6</b>. At the same time, the 2/2-directional valve <b>18</b> in the bypass line <b>16</b> is switched into its blocking position shown so that no fresh pressurized air can reach the pressurized air store via the store pressure line <b>11</b> and fill the pressurized air store unwontedly.

0026The blocked 2/2-directional valve <b>18</b> in the bypass line <b>16</b>, however, prevents that, during the filling of the vehicle tire <b>30</b>, dry and already compressed pressurized air can escape from the pressurized air store <b>7</b> via the 3/2-directional valve <b>32</b> (which is in the pressure position) into the store pressure line <b>11</b> and via the bypass line <b>16</b> from the closed loop of the air supply system and be used to fill the vehicle tire.

0027It is understood that the foregoing description is that of the preferred embodiments of the invention and that various changes and modifications may be made thereto without departing from the spirit and scope of the invention as defined in the appended claims.